You can apply Masters in the US after completing 16 years of undergraduate education.
Since most of the Indian Colleges have 3 year undergraduate program, it is advisable to do one more year of education, could be a diploma or a certificate program to make your education complete of 16 years. The course has to be recognised and accredited.
US universities insist upon a minimum IELTS of 6.0 to 6.5 and Tofel scores of 80 to 90.
The most common visa for students is the F1 visa that is a non-immigrant visa.
It is always beneficial if you start early. You should start 12-18 months in advance before the date of enrolment , you get time to prepare a good application as well as avail scholarships and financial assistance.